1. Field of the Invention
This invention relates to rotary drive apparatus utilizing a cable extending about and secured to a driving element and to a driven element, and, more particularly, to a rotary drive system utilizing a cable terminated at both ends to the driven element through tension springs.
2. Description of the Prior Art
U.S. Pat. No. 4,351,197 (Carson) discloses a rotary drive system in which a threaded screw, driven by a motor, is connected to a driven member, a drum, through a cable connected at both ends to the driven member, the drum. The cable is terminated at one end through a spring arrangement and is terminated at its other end by a solid termination without a spring. It is obvious that the cable may break anywhere along its length. It is also obvious that a break in the cable will result in the free ends of the cable, adjacent to the break, becoming tangled with other cables, if there are a plurality of cables involved. The entanglement will in turn result in substantial problems with the operation of the apparatus.
The apparatus of the present invention provides a solution to the entanglement problem in the event of a cable breakage by utilizing tension springs at both ends of the cable. Thus, in the event of a break in the cable, the free ends of the cable will be retracted by the tension springs. With the tension springs disposed within bores in the driven member, the free ends of the cable will not become entangled with the remaining cable or cables coupling the two members together.